Perhaps we are each talking too generally and need a bit more specificity. If we're talking about premium products in the sense of iPhones, new cars, video game

Perhaps we are each talking too generally and need a bit more specificity. If we're talking about premium products in the sense of iPhones, new cars, video games and other kinds of irregular purchases like that then I expect you're right at least in the short term. But the relevant point of discussion here is what you tend to need from a supermarket in day-to-day household consumables and their respective economy/premium products which contribute to a household's regular expenditures. In the household consumables case, the premium products are definitely still selling.